How do I get over him?

I found out my longtime boyfriend was flirting with another girl online calling her beautiful... I broke up with him but I feel so heartbroken like I can’t go on 💔 i thought we were going to spend our lives together... he hasn’t even messaged me in 3 days or acted like he cares. He still likes the other girls’ posts. We spent every single day together and now that we’re over I don’t know what to do with all the extra time on my hands. I keep checking my phone every couple minutes to see if he’s texted me and checking his facebook to see if he’s online or posted anything. I don’t have any friends anymore because all my time was spent with him. from someone who has been there, how do I get over this?😢